# by default, scan all partitions (/proc/partitions) for MD superblocks.
# alternatively, specify devices to scan, using wildcards if desired.
# Note, if no DEVICE line is present, then "DEVICE partitions" is assumed.
# To avoid the auto-assembly of RAID devices a pattern that CAN'T match is
# used if no RAID devices are configured.
DEVICE partitions

mdadm --assemble --verbose --force /dev/md127 /dev/sd[abcd]
gavemdadm: looking for devices for /dev/md127mdadm: /dev/sda is identified as a member of /dev/md127, slot 1.mdadm: /dev/sdb is identified as a member of /dev/md127, slot 0.mdadm: /dev/sdc is identified as a member of /dev/md127, slot 2.mdadm: /dev/sdd is identified as a member of /dev/md127, slot 3.mdadm: added /dev/sda to /dev/md127 as 1mdadm: added /dev/sdc to /dev/md127 as 2 (possibly out of date)mdadm: added /dev/sdd to /dev/md127 as 3mdadm: added /dev/sdb to /dev/md127 as 0mdadm: /dev/md127 has been started with 3 drives (out of 4).

cat /etc/mdadm/mdadm.con
gave# mdadm.conf## Please refer to mdadm.conf(5) for information about this file.#

# by default, scan all partitions (/proc/partitions) for MD superblocks.# alternatively, specify devices to scan, using wildcards if desired.# Note, if no DEVICE line is present, then "DEVICE partitions" is assumed.# To avoid the auto-assembly of RAID devices a pattern that CAN'T match is# used if no RAID devices are configured.DEVICE partitions

Thanks, there is obviously an issue with /dev/sdc it could infer that the drive is failing. When you post the output of a command can you use </> on the menu bar and copy and paste the full output, makes it easier to read thanks.

Yes, but the layout of my reply got messed up. I copied everything from your post in the correct order.
The one thing i think is weird is the response onmdadm --zero-superblock /dev/sdc
which ismdadm: Unrecognised md component device - /dev/sdc

Funny it shows as ZFS member, because the disk that is replaced is not that disk. I had a few reinstalls after changing the disk though.(initial setup was 4x3TB, then i went to a disk array (20x2TB)and when i got the energy bill i went back to 3x3TBand 1x4TB. I actually made a new array, on a different microserver(i borrowed one) and copied all data from my external enclosure to internal disks. then destroyed the external enclosure.

Can i just remove the correct disks while doing the procedure? That would make sure i won't delete any data right?

You you could, because the other odd thing about your output is that the mdadm.conf file has no reference to an array. If you pull the drives, don't reboot, shutdown then plug the drives back in, then start.

Just copying half a terra of photo's now, after that i will turn it off, remove the correct disks, boot in rescue mode, see if i can completly destroy disk C (or fix it...) and then shutdown, put disks back in, boot.

I will let you know. Copy-ing the photo's will take some time so have to wait for that.. don't want to loose those, i can live without the movies and series and music i collected.